1. Field of the Invention
The present invention relates generally to a disc drive arrangement and more specifically to a so called "slot in"loading type disc drive arrangement which can correctly load discs of different sizes.
2. Description of the Prior Art
Of recent times CD players using the so called "slot in"loading type arrangements have been widely used in connection with automotive vehicle type stereo systems. FIGS. 15 and 16 show a previously proposed slot in loading type arrangement. In these figures a disc loading passage or slot 1 is provided with a disc loading roller 2 which cooperates with a disc 3 for the purposes of moving the disc into an operative position.
When the disc is being loaded the loading roller 2 engages the disc 3 and is rotated in a first predetermined rotational direction. When the disc 3 is unloaded the loading roller 2 is rotated in the opposite rotational direction.
In addition to the loading roller 2, the arrangement includes a guide plate 4 which is located in a manner to engage the surface of the disc 3 opposite to that which the loading roller contacts. As will be appreciated from the drawings, the loading roller 2 is arranged to have a small diameter center portion and outwardly tapering larger diameter end sections. At the same time, the guide plate 4 is arranged so that the surface thereof in contact with the disc is concavely curved. With this arrangement surfaces of the disc 3 are engaged by the loading roller 2 and the guide plate 4 and therefore protected from damage such as scratching, abrasion and the like.
However, with this type of prior art arrangement a problem is encountered that it is difficult to load discs of different size, for example 12cm and 8cm. Viz., in order to permit the larger diameter 12cm discs to be loaded it is necessary to arrange the loading slot width to be sufficiently wide to permit the entry of the larger of the two discs. This requirement also tends to fix many of the other dimensions of the device in a manner whereby when a smaller 8cm diameter disc 5 is loaded, such as shown in FIG. 17, the disc is subject to very little centering and is able to move off center from the position illustrated in solid line to that illustrated in phantom.
To overcome this problem it has been proposed to provide a small disc guide arrangement in the guide slot immediately before the loading roller 2. However, as this guide is fixedly disposed in the loading slot its provision prevents the loading of the larger 12cm discs.
A further problem is encountered in that the disc guide plate 4 which is located adjacent to the tapered loading roller 2 is arranged to be concave for the purpose of ensuring that contact between the roller and the guide plate only occurs at the periphery of the disc which is not used for recording purposes. In the event that sufficient clearance is set to permit the entry of a large diameter disc, when a small diameter disc is inserted, an overly large clearance occurs in the region that the disc should be gripped. The result is that slippage occurs which often leads to delayed or improper loading. Conversely, if the clearance is set for small diameter discs, when a large diameter one is inserted excessive contact between the guide plate and the surface of the disc on which material is recorded tends to occur and tends to lead to scratching and other like damage.